A heat slug leadframe provides mechanical support to semiconductor packages during assembly into finished products. FIG. 1A illustrates a prior art heat slug leadframe 100. The heat slug leadframe 100 has a N×M matrix of heat slug pads 105 coupled together or to the frame 120 using tie bars 110a, 110b. As illustrated, the tie bars 110a, 110b couple vertically and horizontally adjacent heat slug pads 105 together. In particular, each heat slug pad uses tie bars 110a, 110b on all sides of the heat slug pad to couple to other heat slug pads 105 and/or to the frame 120. Vertical and horizontal cuts 115a, 115b across the matrix during singulation are thus needed to separate the heat slug pads 105 from each other and the frame. Due to the time required to take the multiple passes (i.e., vertical passes and horizontal passes) across the matrix for singulation, the prior art leadframe 100 therefore has a low units per hour (UPH) output value. Further, the required passes across the matrix not only causes high blade wear, but singulating the heat slug pads 105 with packages (not illustrated) coupled thereto has a high potential of cracking or chipping these packages. These cracked or chipped packages are unusable. Such damages can become costly.
FIG. 1B illustrates a cross section view along the line A-A of the prior heat slug leadframe of FIG. 1A. There are two types of tie bars. The first type of tie bar 110b1 is not etched and has the same thickness as a heat slug pad 105. The second type of tie bar 110b2 is etched and has, for example, half the thickness as a heat slug pad 105 to help reduce or minimize blade wear. However, a heat slug leadframe having the second type of tie bar 110b2 has the same disadvantage as a heat slug leadframe having the first type of tie bar 110b1 in that it has a low UPH and a high potential of damaging the packages coupled thereto due to the required multiple passes across the matrix of heat slug pads for singulation. What is needed is a leadframe that requires less passes across the leadframe during singulation to reduce or minimize blade wear and/or the potential of cracking or chipping packages thereon.